Control rod and control rod assembly

Abstract

The invention mainly relates to the technical field of nuclear reactors, in particular to a control rod and a control rod assembly. The control rod comprises an upper end plug, a cladding tube and a lower end plug which are connected in sequence, and an absorber core block positioned in the cladding tube, the upper end plug and the lower end plug each comprise a maximum light pillar area and an assembly area, and the outer diameter of the cladding tube is smaller than the outer diameter of the maximum light pillar area of the upper end plug and the outer diameter of the maximum light pillar area of the lower end plug. The outer diameter size of the cladding tube of the control rod is reduced relative to the size of a conventional fuel rod, the flow area between the control rod and the wall of the guide tube is increased, and the purposes of reducing flow resistance and increasing and decreasing bypass flow are achieved; and secondly, the outer diameter size of the cladding pipe is reduced compared with the size of a conventional fuel rod, so that the cladding pipe is not prone to making contact with the guide pipe and the guide cylinder of the driving mechanism in the downward inserting or lifting process, and abrasion to the surface of the cladding pipe is reduced.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of nuclear reactors, and in particular to a control rod and a control rod assembly. Background Art

[0002] The start and stop of nuclear reactors and the regulation of nuclear power are mainly controlled by control rods. The material in the control rods can strongly absorb neutrons and can control the chain fission reaction in the reactor. The control rods are also assembled in the form of components. When the reactor is not in operation, the control rods are inserted into the core. When the reactor is turned on, the control rods are lifted up and the height of the control rods is adjusted as needed during operation. In the event of an accident, all control rods will automatically fall down quickly to stop the chain fission reaction in the reactor.

[0003] like Figure 1 As shown, the conventional control rod 100 is welded by an upper end plug 11, a lower end plug 13 and a cladding tube 12, wherein the outer diameters of the connection between the upper end plug 11, the lower end plug 13 and the cladding tube 12 are consistent. Figure 2 As shown in the figure, under the design condition, the control rod 100 is inserted into the guide tube, and the gap between the outer diameter of the cladding tube and the inner diameter of the guide tube is the control rod bypass flow channel D1. Under low core flow, the bypass flow channel D1 in the guide tube corresponding to the existing conventional control rod structure is narrow, resulting in a decrease in the bypass flow rate, and the control rod temperature may exceed the design limit; in addition, during the operation of the core, the surface of the control rod cladding often contacts the guide tube, resulting in cladding tube wear. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a control rod and a control rod assembly to solve the problem that the temperature of the control rod may exceed the design limit under low core flow rate of the existing control rod.

[0005] In order to solve the above technical problems, the present invention provides a control rod, comprising: an upper end plug, a cladding tube and a lower end plug connected in sequence, and an absorber core block located in the cladding tube; the upper end plug and the lower end plug both include a maximum light column area and an assembly area, and the outer diameter of the cladding tube is smaller than the outer diameter of the maximum light column area of ​​the upper end plug and the lower end plug.

[0006] Optionally, the outer diameter of the maximum light column area is 9.65 mm, and the outer diameter of the cladding tube is 8.6-9.5 mm.

[0007] Optionally, the upper end plug is connected to the cladding tube via its own assembly area, and the lower end plug is connected to the cladding tube via its own assembly area, and the assembly area adopts a stepped assembly structure with a guide surface.

[0008] Optionally, the assembly area includes an assembly point and a guide surface, and the maximum diameter of the assembly point is 7.77 mm.

[0009] Optionally, the inclination angle of the guide surface is 4° to 6°.

[0010] Optionally, the length of the assembly area is 6.25-6.68 mm.

[0011] Optionally, the diameter of the absorbent core block is 6.88 mm.

[0012] Optionally, the inner diameter of the cladding tube is 7.35-7.76 mm.

[0013] In order to solve the above technical problems, the present invention provides a control rod assembly, comprising: a control rod and a guide tube as described in the present application; the control rod is inserted into the corresponding guide tube, and the gap between the outer diameter of the cladding tube of the control rod and the guide tube ranges from 0.8mm to 1.4mm.

[0014] Optionally, the outer diameter of the maximum light column area of ​​the upper end plug and the lower end plug of the control rod and the gap between the guide tube ranges from 0.75mm to 1.0mm.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The outer diameter of the cladding tube of the control rod of the present invention is reduced relative to the size of conventional fuel rods, increasing the flow area between the control rod and the guide tube wall, thereby achieving the purpose of reducing flow resistance and increasing or decreasing bypass flow; secondly, the outer diameter of the cladding tube of the present invention is reduced relative to the size of conventional fuel rods, making it difficult for the cladding tube to contact the guide tube and the guide cylinder of the driving mechanism during the insertion or lifting process, thereby reducing the wear on the surface of the cladding tube; the outer diameter of the absorber core block of the control rod of the present invention is reduced relative to the size of conventional fuel rods, thereby reducing the heat generation per unit length of the absorber core block. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the present application. They are included and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and together with the present specification serve to explain the principles of the present application. In the accompanying drawings:

[0018] Figure 1 This is a schematic diagram of the structure of a conventional control rod.

[0019] Figure 2 This is a schematic diagram of a conventional control rod and guide tube combination.

[0020] Figure 3 is a schematic structural diagram of a control rod according to an embodiment of the present invention.

[0021] Figure 4 yes Figure 3 Schematic diagram of the structure of the upper end plug and the lower end plug.

[0022] Figure 5 is a schematic structural diagram of a control rod assembly according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0024] like Figures 1-2 As shown in the figure, the outer diameters of the upper and lower end plugs of conventional control rods are consistent with those of the cladding tube, and the volume of the absorber core block per unit length is relatively large, resulting in a narrow gap between the outer diameter of the cladding tube of the control rod and the guide tube. Under low flow rates, the bypass flow rate is reduced and the control rod temperature may exceed the design limit. In addition, during the operation of the core, the surface of the control rod cladding often contacts the guide tube and the guide cylinder of the drive mechanism, causing wear or even wear-through.

[0025] The purpose of the present invention is to design a control rod of a new structure to achieve the following effects:

[0026] 1) Under low flow rate, the control rod bypass flow rate is increased;

[0027] 2) The volume of the absorber per unit length is reduced, and the heat generated by the absorber per unit length is reduced;

[0028] 3) The guiding and connecting functions of the upper and lower end plugs of the control rod are maintained. The number of contacts between the cladding tube and the guide tube and the guide tube of the driving mechanism under the new structure is reduced, which can reduce the wear of the control rod cladding tube.

[0029] Figure 3 is a schematic structural diagram of a control rod according to an embodiment of the present invention. Figure 4 yes Figure 3 Schematic diagram of the structure of the upper end plug and the lower end plug. Figures 3-4 As shown, the control rod 300 includes an upper end plug 31, a cladding tube 32 and a lower end plug 33 connected in sequence, and an absorber core block 34 located in the cladding tube 32. Optionally, the absorber core block 34 is compressed by a compression spring 35. The upper end plug 31 includes a maximum light column area 311 and an assembly area 312. The lower end plug 33 includes a maximum light column area 331 and an assembly area 332. The outer diameter of the cladding tube 32 is smaller than the outer diameter of the maximum light column area 311, and the outer diameter of the cladding tube 32 is also smaller than the outer diameter of the maximum light column area 331.

[0030] In some embodiments, the outer diameter of the maximum light column area 311 is 9.65 mm, the outer diameter of the maximum light column area 331 is 9.65 mm, and the outer diameter of the cladding tube 32 is 8.6-9.5 mm.

[0031] In some embodiments, the inner diameter of the cladding tube 32 is 7.35-7.76 mm.

[0032] Figure 5 FIG. 1 is a schematic diagram of the structure of a control rod assembly according to an embodiment of the present invention. Figure 5 As shown, the control rod assembly 500 includes a control rod 300 and a guide tube 51. The control rod 300 is inserted into the corresponding guide tube 51. The gap between the outer diameter of the cladding tube 32 of the control rod and the guide tube 51 is the bypass flow channel D2.

[0033] In some embodiments, the bypass flow channel D2 ranges from 0.8 mm to 1.4 mm.

[0034] The outer diameter of the cladding tube of the present invention is reduced relative to the size of conventional fuel rods, thereby increasing the flow area between the control rod and the guide tube wall, thereby achieving the purpose of reducing flow resistance and increasing or decreasing bypass flow.

[0035] Secondly, the outer diameter of the cladding tube of the present invention is reduced relative to that of conventional fuel rods, so that the cladding tube is not easily contacted with the guide tube and the guide cylinder of the driving mechanism during the insertion or lifting process, thereby reducing the wear on the surface of the cladding tube.

[0036] The maximum light column area of ​​the upper end plug and the lower end plug can play a role of guidance and lateral support in the guide tube or the guide cylinder of the driving mechanism.

[0037] like Figures 3-4 As shown, the upper end plug 31 is connected to the cladding tube 32 through its own assembly area 312, and the lower end plug 33 is connected to the cladding tube 32 through its own assembly area 332. The assembly areas 312 and 332 adopt a stepped assembly structure with a guide surface.

[0038] In some embodiments, the length of the assembly area 312 is 6.25-6.68 mm, and the length of the assembly area 332 is the same as the length of the assembly area 312 .

[0039] The assembly area 312 includes an assembly point 3121 and a guide surface 3122. The assembly area 332 includes an assembly point 3321 and a guide surface 3322. In some embodiments, the maximum diameter of the assembly point 3121 is 7.77 mm, and the inclination angle of the guide surface 3122 is 4° to 6°. Optionally, the structural dimensions of the assembly point 3321 and the guide surface 3322 are the same as those of the assembly point 3121 and the guide surface 3122. The dimensions of the assembly points of the upper end plug, the lower end plug and the cladding tube can ensure smooth assembly and connection of the end plug and the end of the cladding tube.

[0040] like Figure 5 As shown, the gap between the outer diameter of the maximum light column area 331 and the guide tube 51 is the bypass flow channel D3. In some embodiments, the bypass flow channel D3 ranges from 0.75 mm to 1.0 mm.

[0041] In some embodiments, the diameter of the absorber pellet is 6.88 mm. The outer diameter of the absorber pellet of the present invention is reduced relative to the size of conventional fuel rods, thereby reducing the heat generated per unit length of the control rod absorber pellet.

[0042] Compared with conventional control rods, the outer diameter of the cladding tube of the control rod of the present invention is smaller than the maximum light column area size of the upper end plug and the lower end plug of the control rod, thereby increasing the flow area between the control rod and the guide tube wall, thereby achieving the purpose of reducing flow resistance and increasing or decreasing bypass flow; secondly, the cladding tube is not easy to contact with the guide tube and the guide cylinder of the driving mechanism during the insertion or lifting process, thereby reducing the wear on the surface of the cladding tube.

[0043] In some embodiments, the structure of the upper end of the upper end plug 31 matches the structure of the connecting handle component. For example, the upper end of the upper end plug 31 adopts a unified external thread connection structure, and the external thread model matches the connecting handle component, so that the control rod component and the connecting handle component can be assembled.

[0044] The basic concepts have been described above. Obviously, for those skilled in the art, the above invention disclosure is only used as an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0045] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0046] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of the present application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the subject of the present application requires more features than the features mentioned. In fact, the features of the embodiment are less than all the features of the single embodiment disclosed above.

[0047] As shown in this application, unless the context clearly indicates an exception, the words "a", "an", "a kind" and / or "the" do not refer to the singular, but also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0048] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0049] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0050] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0051] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0052] It should be understood that when a component is referred to as being "on another component," "connected to another component," "coupled to another component," or "contacting another component," it may be directly on, connected to, coupled to, or contacting the other component, or there may be intervening components. In contrast, when a component is referred to as being "directly on another component," "directly connected to," "directly coupled to," or "directly contacting" another component, there are no intervening components. Similarly, when a first component is referred to as being "electrically in contact with" or "electrically coupled to" a second component, there is an electrical path between the first component and the second component that allows current to flow. The electrical path may include capacitors, coupled inductors, and / or other components that allow current to flow, even without direct contact between conductive components.

[0053] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining the digits. Although the numerical domains and parameters used to confirm the breadth of the range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0054] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the present application.

Claims

1. A control rod, characterized in that: include: An upper end plug, a cladding tube and a lower end plug connected in sequence, and an absorbent core block located in the cladding tube; The upper end plug and the lower end plug both include a maximum light column area and an assembly area, and the outer diameter of the cladding tube is smaller than the outer diameter of the maximum light column area of ​​the upper end plug and the lower end plug.

2. The control rod according to claim 1, characterized in that The outer diameter of the maximum light column area is 9.65 mm, and the outer diameter of the cladding tube is 8.6-9.5 mm.

3. The control rod according to claim 1, characterized in that The upper end plug is connected to the cladding tube through its own assembly area, and the lower end plug is connected to the cladding tube through its own assembly area. The assembly area adopts a stepped assembly structure with a guide surface.

4. The control rod according to claim 3, characterized in that The assembly area includes an assembly point and a guide surface, and the maximum diameter of the assembly point is 7.77 mm.

5. The control rod according to claim 4, characterized in that The inclination angle of the guide surface is 4° to 6°.

6. The control rod according to claim 3, characterized in that The length of the assembly area is 6.25-6.68 mm.

7. The control rod according to claim 1, characterized in that The diameter of the absorbent core block is 6.88 mm.

8. The control rod according to claim 2, characterized in that The inner diameter of the cladding tube is 7.35-7.76 mm.

9. A control rod assembly, characterized in that: include: The control rod and guide tube according to any one of claims 1 to 8; The control rod is inserted into the corresponding guide tube, and the gap between the outer diameter of the cladding tube of the control rod and the guide tube is in the range of 0.8 mm to 1.4 mm.

10. The control rod assembly according to claim 9, characterized in that The outer diameter of the maximum light column area of ​​the upper end plug and the lower end plug of the control rod and the gap between the guide tube ranges from 0.75mm to 1.0mm.

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